The present invention relates generally to integrated circuit (IC) design, and, more particularly, to waveguide designs in an integrated circuit.
In semiconductor devices, transmission lines are always needed to transmit signals either on a chip level or on a board level. There are four major transmission line constructions: microstrip, stripline, coaxial line and waveguide.
A microstrip is a thin, flat electrical conductor separated from a ground plane by a layer of insulation or an air gap. A stripline is similar to a microstrip, except that the stripline is sandwiched between two ground planes and respective insulating layers. A coaxial line has a conducting line in the center and a second conducting layer running all the way around the exterior circumference. The inner and outer conductors are separated by a dielectric layer. A waveguide is simply an all-around metal enclosure from a cross-sectional view.
It is relatively easy to form microstrip and stripline in integrated circuits as they are two dimension structures. But waveguide has a number of advantages over microstrip and stripline. It is completely shielded so that an excellent isolation between adjacent signals can be obtained. It can transmit extremely high peak powers and has very low loss, almost negligible, at microwave frequencies.
Therefore, it is desirable to be able to build waveguide transmission lines in integrated circuits.